This invention relates to a catalyst for producing polyurethane foam and a composition for producing polyurethane foam containing such a catalyst.
Heretofore, (a) amine compounds, for example, triethylenediamine, 1,4-diazabicyclo(2,2,2)octane, N-methylmorpholine, N,N-dimethylethanolamine, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, 1,8-diazabicyclo(5,4,0)-undecene-7, N-methylpiperadine, etc. and (b) organic tin compounds, for example, dibutyl tin dilaurate, dibutyl tin diacetate, etc. are used as the catalyst for producing polyurethane foam [e.g. J. H. Saunders, K. C. Frisch: Polyurethanes, Chemistry and Technology, Part 1, Chemistry, pages 162-203, (1978), Robert E. Krieger Publishing Company, New York; Journal of Applied Polymer Science, Vol. IV, Issue No. 11, pages 207-211 (1960)].
Generally, polymethane foam can be obtained by mixing a liquid A comprising a compound containing at least one active hydrogen atom in a molecule, determined according to Zerewitinoff method (including water), a foaming agent, a catalyst, and, if necessary, a foam-controlling agent, with a liquid B comprising an organic polyisocyanate compound as the main component.
The conventional catalysts as mentioned above have a poor compatibility with the organic polyisocyanate compound, and no uniform foam can be obtained unless the liquids A and B are thoroughly mixed together at the production of polyurethane foam. That is, in the case of the conventional catalysts, reaction is locally promoted, if the mixing is not carried out thoroughly, and polyurethane foams having uneven color distribution at the inside are liable to be produced.